The ‘square waves’ that are so dangerous you should leave the sea immediately

IF you see "square waves" next time you're in the sea, you should get out as quickly as possible.

Also known as cross seas, they may look pretty but are actually extremely dangerous - and have even caused shipwrecks.

Square waves can be found out in the open ocean as well as near the coast, and are formed by waves moving in opposite directions.

This happens when two separate weather systems collide.

The waves then create a chequerboard affect on the sea, with a grid system of squares on the surface.

They look gentle from above, but are actually similar to rip tides, which are extremely hard to escape from.

Anyone caught in the water is likely to struggle to escape them, as they will be fighting two different waves at the same time.

According to the , they have even caused a number of shipwrecks over the years due to the battling waves.

If you do want to see the waves - from a safe distance on land - they can often be spotted in France on the Isle de Re, according to Travel + Leisure.

Located near La Rochelle, tourists can climb the lighthouse to see the phenomenon from above.

Waves around the world are getting stronger thanks to climate change, a report has warned.

When combined with rising sea levels, the risk of damage to coastal areas grows significantly, and has scientists worried about our preparedness.